The present invention relates to an ultrasonic surgical tool, such as an ultrasonic laparoscopic tool for cutting soft body tissues. More particularly, but not exclusively, it relates to such a tool having an operative tip that is profiled to improve the ergonomics of its use.
Ultrasonically-vibrated cutting tools have proven of major benefit for surgery, particularly laparoscopic surgery (so-called “keyhole” surgery). An elongate, narrow surgical tool, usually together with a fibre-optic endoscope viewing system, is introduced through a small incision into a patient's body and directed to an exact region of tissue requiring surgery. In more complex procedures, further tools may be introduced, by way of further incisions, then directed to the same site, although this is avoided wherever possible. In any case, a basic aim of laparoscopic surgery is to minimise the size and number of incisions (or “ports”) made into the patient's body.
The constraints inherent in working with long, narrow tools in a confined space under remote viewing (for example on a monitor screen) mean that ergonomic design of laparoscopic tools is of paramount importance.
Ultrasonically-vibratable tools bring significant benefits in such minimally invasive procedures, as they may be selectably energised so as to cut only target tissues, and they may easily be adapted to cauterise tissue as they cut. Thus, blood vessels may be both severed and sealed in one operation, for example, significantly reducing bleeding. Such haemostatic cutting is of particular benefit in laparoscopic surgery, where visibility is at a premium.
Torsional-mode ultrasonic vibrations have proven particularly effective, since they may be transmitted efficiently and precisely into selected target tissues with minimal extraneous leakage of ultrasonic energy, whereas the alternative longitudinal-mode (or compression-wave) ultrasonic vibrations may lead to undesirable propagation of energy longitudinally out of a distal end of a tool into adjacent (non-target) tissues.
A conventional ultrasonically-vibratable laparoscopic tool, whether torsional-mode or longitundinal-mode, comprises an operative element or elements extending longitudinally from a distal end of an elongate waveguide. A surgeon manipulates the tool by grasping a handgrip mounted adjacent the proximal end of the waveguide, which extends through a restricted port into a patient's body. The operative elements are thus ideally positioned to be employed on tissues substantially directly in line with the axis of the waveguide. However, to work on tissue located to one side of the axis of the waveguide, the surgeon must partially withdraw and realign the tool, constrained by the dimensions of the port and at all times manipulating the tool by its proximal end. The continual repositioning required in a complex procedure may rapidly lead to fatigue on the part of the surgeon. There is hence a need for an ergonomically superior tool that allows the surgeon to work for longer and with improved control.
As mentioned above, another important ergonomic issue in laparoscopy is clear visualisation of the operative elements of the tool and the target tissue. An endoscope viewing system is inserted through a further incision, but this may arrive at the target tissue at such an acute angle to the tool that three dimensional visualisation is difficult.
It is hence an object of the present invention to provide an ultrasonic cutting and/or coagulating tool that obviates the above disadvantages and allows a user to conduct laparoscopic surgery more conveniently and with improved control.